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February 16, 2010

Lists, Part 1: Parallelism

Timothy McAdoo by Timothy McAdoo

When I feel overwhelmed with tasks, I often make a list (or two or three).

Because making lists helps me organize my thoughts, I also tend to begin a rough draft of a writing assignment as a series of ideas or bullet points. In most cases, I will expand and expound on these ideas, turning them into complete paragraphs. But, sometimes a list helps clarify an idea as well. As the Publication Manual of the American Psychological Association says, a list “helps the reader understand the organization of key points.”

In the first five parts of this six-part series about lists in APA Style, I will cover three aspects of list style and punctuation:
  • parallelism,
  • serial commas, and
  • semicolons.
And, I’ll detail three types of lists:
  • lettered,
  • numbered, and
  • bulleted.
Finally, in Part 6 I’ll summarize and post a table showing the typical uses for each type of list.


For a general guideline about creating lists, the Manual states that “all items should be syntactically and conceptually parallel” (p. 63). This may seem obvious, but it’s easy to use wording that’s not precisely parallel when first getting your ideas onto paper. On the second draft, assess the structure of your lists carefully.

In this example, I’ve underlined the elements that should be parallel in syntax:

Participants were told to study each picture, to turn the page when the bell rang, and that they should ask about anything unclear in the instructions.

That sentence conveys the meaning, but the lack of parallelism weakens its impact. Consider this alternative:

Participants were told to study each picture carefully, to turn the page when the bell sounded, and to ask about anything they found unclear in the instructions.

And, creating parallelism is not just about making the sentence "sound right." A parallel sentence structure makes it easier for a reader to compare like items and to follow sequences of action, much like a well-structured table makes it easier for a reader to scan and compare entries across rows.

In the following, the writer may think he or she is avoiding redundancy by omitting two instances of “Practice Group”:

Children in Practice Group A and in Groups B and C received no visual stimuli, whereas those in Practice Group D were shown an image of a lion.

But, in technical writing, this type of inconsistency can cause confusion. Was there a substantial difference between a “practice group” and a “group”? Probably not, but it might give your reader pause, especially if both terms are used throughout your paper.

There are many ways you might rewrite this sentence with a parallel structure. Here’s one example:

The researchers provided no visual stimuli to children in Practice Groups A, B, and C, whereas researchers projected an image of a lion for children in Practice Group D.

More examples of parallel structure can be found on pages 84–86 of the Manual.

More to Come

In Part 2, I’ll discuss APA Style guidelines for using commas and semicolons in lists.

Lists, Part 1  |  Lists, Part 2  |  Lists, Part 3


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